The origin, distribution, and depositional history of gravel deposits on the Beaufort Sea Continental Shelf, Alaska

Abstract

Two distinct gravel populations are present on the Beaufort Sea continental shelf. First, a geographically arcuate deposit that is convex seaward has been designated as the Chert Facies. This deposit is restricted to landward of the 10 meter bathymetric contour and west of Heald Point. The Chert Facies, originally a fluvial gravel deposit and probably part of the basal transgressive, represents reworked Gubik Formation. The Chert Facies is derived from the Brooks Range. The second population is the Dolomite Facies. This facies is a blanket deposit covering much of the shelf and occurs in most water depths greater than 10 meters. The Dolomite Facies extends on land into the Quaternary Gubik Formation east of Prudhoe Bay and probably to Point Barrow. Rocks of the Dolomite Facies are exotic to Alaska and represent ice rafted clasts. The distribution of the Dolomite Facies shelf gravel indicates an easterly source compatible with a proposed provenance surrounding the Amundsen Gulf of the Canadian Archipelago. Radiocarbon dates from undisturbed sediment underlying the gravel on the upper slope indicate that low Holocene sedimentation rates are the reason for gravel exposure in this region and on the outer shelf. Considerations of sea level fluctuations, possible times available for the transportation of gravel from the proposed source area to the study area, and radiocarbon dates indicate influxes of ice rafted debris during the mid-Wisconsin transgression and probably between 15, 000-10,000 years B. P. Correlation of the Gubik Formation at Heald Point with the Barrow unit of the Gubik Formation at Point Barrow on the basis of incorporated dolomite and orthoquartzite clasts is suggested.